In the construction industry, there are a great number of window designs which can be used for various manmade structures. For windows that are intended to be manually operated in order to open and close, there are also numerous available designs. For windows that are manually operated, consideration must be given as to providing a user the ability to operate the window without exerting an unnecessary amount of force.
One type of window design that is commonly used in residential and commercial structures is the hung window. A hung window typically includes two or more sashes arranged in a vertical orientation, i.e., one sash above and the other sash below. One of the sashes may typically be operated to open or close. Because of the weight of the operable sash that must be overcome in order to move the operable sash, a number of designs have been developed in order to mechanically assist the user thereby reducing the amount of force necessary to operate the sash in order to maintain the sash in any desired position.
Two very common ways to mechanically assist in operation of the lower sash includes spiral balances or block and tackle balances. In most cases, both the spiral balances and the block and tackle balances are spring assisted. There are numerous disadvantages to both spiral and block and tackle balances. For such spring assisted balances, they are difficult to repair because the window must be disassembled in order to access the working parts for replacement. Spring assisted balances easily wear out and there are limits as to the weight of an individual sash that can be operated with such balances.
Despite the numerous designs that exist for hung windows, there still exists a need for a hung window which has a simple yet reliable construction, and allows a user to operate the sashes with a minimum effort, regardless of the size or weight of the sashes.